public class StairTest {

  public static void main(String[] args) {
    System.out.println(count(Integer.parseInt(args[0])));
  }

  private static int count(int number) {
    if (number == 1 || number == 0)
      return 1;
    else
      return count(number - 1) + count(number - 2);
  }
}
